A novelist can take as long as he likes to write. And can go back and revise. The DM doesn't have to make it all up himself.
In a gaming session, something like this can work to save the day in an impossible situation, IF the player, or the DM is quick on his feet. But the novelist can put the whole story (or outline) on the shelf until he comes up with an adequate resolution. He can even bounce the notion off other people and see who comes up with a brilliant notion. And if he concludes that having the bard survive that way doesn't fit the story's mood or theme, he can resolutely wipe out the bard's capture -- even if he comes that to conclusion after fifty thousand more words.
Likewise, if the characters really, really, really need a certain magical object, not only can the novelist ensure that they fought the right monster to find it, and choose to keep it, he can go back and retroactively put it into the hoard (or shop, or mentor's armory). In a session, the DM's pretty much stuck with planting it again, near the problem, or having a magical object (even if apparently non-magical) suddenly manifest the right powers under the right circumstances. The novelist, of course, can also make an object manifest powers under the the right circumstances. And then he can go back and plant the foreshadowing to make it plausible and not a rabbit pulled out of a hat -- though, to be sure, players probably care less about foreshadowing than readers do.
On the third hand, the DM can turn the players loose and see what they work out. Maybe they can discover a reasonable solution that doesn't involve the object even if the DM can't imagine it.